O.  Breuss, ?Byssoloma maderense is not endemic to Macaronesia?, Evansia, vol. 33, pp. 54-62, 2016.

C.  Gueidan, Savic, S., Thüs, H., Roux, C., Keller, C., Tibell, L., Prieto, M., Heiðmarsson, S., Breuss, O., Orange, A., Fröberg, L., Wynns, A. A., Navarro-Rosinés, P., Krzewicka, B., Pykälä, J., Grube, M., and Lutzoni, F., ?Generic classification of the Verrucariaceae (Ascomycota) based on molecular and morphological evidence: recent progress and remaining challenges?, Taxon, vol. 58, pp. 184-208, 2009.

O.  Breuss, ?Placidium?, in Lichens of Great Britain and Ireland, London: British Lichen Society, 2009, pp. 708-710.

O.  Breuss, ?Revision der Flechtengattung Placidiopsis {Verrucariaceae)?, Oesterreichisches Zeitschrift für Pilzkunde, vol. 5, pp. 65-94, 1996.

O.  Breuss, ?Placidiopsis?, in Lichens of Great Britain and Ireland, London: British Lichen Society, 2009, pp. 707-708.

O.  Breuss, ?Catapyrenium?, in Lichens of Great Britain & Ireland, London: British Lichen Society, 2009.

O.  Breuss, ?Die Flechtengattung Catapyrenium (Verrucariaceae) in Europa?, Stapfia, vol. 23, p. 174 pp, 1990.

O.  Breuss, ?An updated world-wide key to the catapyrenioid lichens (Verrucariaceae)?, Herzogia, vol. 23, pp. 205-216, 2010.

O.  Breuss, ?Über einige wenig bekannte Verrucaria-Arten (Lichenes, Verrucariaceae)?, Österreichische Zeitschrift für Pilzkunde, vol. 3, pp. 15-20, 1994.